1. Field of the Invention
The present invention relates to a surface-shaping method, and more particularly to a method of forming a series of hills and valleys alternately arranged at a predetermined pitch on the surface of a given workpiece.
2. Related Arts
Referring to FIG.7, a solar cell 50 has minute hills 51 and valleys 52 alternately formed on its surface, thereby increasing the solar absorption rate and accordingly the rate at which electric power can be produced from sunlight.
A drum-like grindstone 55 having pulverized diamond deposited on its surface is fixed to a rotary spindle 56. The drum 55 has a series of hills 51 and valleys 52 alternately arranged at the same pitches P of peak 54-to-peak 54 intervals (or bottom 53-to-bottom 53 intervals) as the solar cell 50, which is to be provided. The height H measured from the bottom 53 of the valley 52 to the peak 54 of the hill 51 in the drum 55 is equal to the corresponding height measured in the solar cell. In short, the drum 55 has the same saw-toothed pattern as the solar cell, so that the saw-toothed pattern may be transferred from the grindstone 55 to the workpiece W.
In making the saw-toothed grooves on the workpiece W the hill-and-valley arrangement of the grindstone 55 is pushed against the surface of the workpiece. The machining gap remaining therebetween, therefore, decreases gradually toward the tight fit. Accordingly the grinding resistance increases with increase of the bite amount. Also, it is increasingly difficult that the cooling water flows into the ever decreasing gap. Finally, no cooling water is permitted to reach the blade-and-workpiece contact. The solar cell thus produced is of lower quality.
In transferring the valleys from the grindstone to the workpiece to form the corresponding hills therein the exactness of the hill shape thus formed in the workpiece is lowered, compared with the original shape.
There has been, therefore, a demand for decreasing the grinding resistance, and for supplying the machining gap with sufficient amount of cooling water, thereby improving the quality of products.